Tuned armature electromagnetic motor



Nov. 3, 1964 B. FUTTERER 3,155,855

TUNED ARMATURE ELECTROMAGNETIC MOTOR Filed Feb. 27, 1961 Inventor W50 WW The present invention relates to an oscillating armature drive for use in dry shaving apparatuses wherein an armature adapted to oscillate opposite a stationary electromagnet and fixed to an oscillating lever forms, together with one or more springs, a mechanical oscillating system and concerns a special arrangement in the shaver housing or on a mounting plate for achieving undisturbed operation.

In a known form of construction of this kind the mechanical oscillating system consists of an oscillating armature and two oscillator springs which are arranged between stationary supports disposed perpendicular to the axis of the springs, on both sides of the oscillating lever and obliquely in the direction of the armature in such manner that their spring axes from an obtuse angle with the longitudinal axis of the oscillating lever as angle bisectors. A system of this kind is neither tunable in its resonance position or in its amplitude.

According to another known form of construction the mechanical oscillating system has two oscillator springs arranged co-axially and on both sides of the oscillating lever, the outer supports of these oscillator springs being axially displaceable by means of a screw-threaded memher, so that the length of the springs can be altered. In this way and in contrast to the previously mentioned form or" construction the springs can be adjustably pro-stressed and the amplitude of the armature oscillation be altered, but the resonant frequency of the system cannot itself be atlected.

Tuning of the mechanical oscillation system with reference to the frequency of the electromagnet is known in a third form of construction wherein two oscillator springs are disposed co-axially and on both sides of the oscillating lever in stationary supports; in this arrangement the sprin s-A drich have a full or nearly full number of turns-are rotated. In both cases the arrangement of the oscillator springs vertical to the oscillator lever longitudinal axis has the drawback that the oscillating lever bearing is subjected to an increasing loading in the direction of the longitudinal axis of the oscillating lever to the electromagnet; this increasing loading causes increased operational noise in consequence of the bearing clearance and in time throwing out of the bearing. With the lastmentioned arrangement it has been attempted to counter this drawback by positioning the stationary outer supports obliquely to the common axis of the springs and directing them towards the armature. It turned out however that the helical springs were in this way caused to bend into an S-shape which shortens their operational life.

The invention consists in removing the drawbacks of these known forms of construction and combining its favourable features so as to form a new construction of oscillator armature drive.

This is favourably achieved by combining the individually known features to form an oscillating armature drive wherein the oscillator springs are arranged as helical springs on both sides of the oscillating lever and obliquely in the direction of the armature between supports which are disposed vertically to the springs axis and of which at least one is axially displaceable, these springs having a full or nearly full number of turns so that their spring constants and so the resonant frequencies of the system can be altered by turning the spring in the supports.

atent Through the obtuse-angled arrangement of the oscillator springs by which the latter are directed towards the electromagnet, the oscillating lever is continuously loaded-even during zero crossover of the current-in one direction only i.e. by a tensional force towards the electromagnet.

Through the axial displaceability of at least one spring support in conjunction with the full or nearly full number of turns of the oscillator springs there is achieved, as a special advantage, a division of functions in tuning the system in that the resonant frequency of the system can be adjusted by turning the springs and the amplitude be set, via alteration or" the initial air gap and independently of the resonant frequency, merely by shifting one or both sprin supports. The frequency adjustment has a small reaction on the amplitude, for which reason it is suitably undertaken first of all.

An embodiment of the invention is hereinafter decribed with reference to the accompanying drawing which shows the construction of an oscillating armature drive in the rest position with cutter head illustrated only diagrammatically and helical springs arranged in lateral supports on a mounting plate only partially shown.

01 the stator plates rigidly connected to the mounting plate l-together with the field coil of the stator platesthere is only shown the two pole shoes, 2, 3 which form a mechanical and electromagnetically driven oscillating system together with the armature 5 which is arranged on oscillating lever 4 and the two helical springs 6, 7. The oscillating lever made of thermoplastic synthetic material is pivotably mounted about the pin 8 on the mounting plate l and has two moulded lugs 9 and it) for mounting the two helical springs on the side of the oscillating lever, these springs being mounted on the side of the housing on two flanges ll, 12 angled oil laterally from the plane of mounting plate ll. Of these fianges 11 constitutes a stationary support while the other support can be moved by means of screw-threaded member 13 which is arranged in flange l2 and on whose cylindrical extension is applied a plate carrying the helical spring. By turning the screvwthreaded member ll?) helical spring 7 can, for example, be compressed and so the distance a between the inner edge of the left pole shoe 2 and the edge of the armature be altered, and also the amplitude of the mechanical oscillations of the oscillating armature. As the helical springs have a full, or nearly full, number of turns i.e. their two spring ends either lie opposite one another on a cylindrical surface line or are offset by up to approximately relative to one another, it is possible-apart from the amplitude tuning-to tune the resonant frequency of the system by turning the springs.

I claim:

1. An oscillating armature drive for a dry shaving apparatus comprising, in combination, support means; an elongated oscillating lever mounted intermediate the ends thereof on said support means tiltable about an axis extending transverse to the elongation of said lever; and armature fixed to one end of said lever; electromangetic means mounted on said support means and cooperating with said armature for oscillating said lever between a rest position in which said armature is laterally displaced with respect to said electromagnetic means and an attracted position in which said armature is attracted by said electromagnetic means; a pair of coil springs operatively connected at opposite ends thereof to said lever and to said support means and respectively extending to opposite sides of said lever obliquely inclined there-to so as to provide on said lever a force component directed toward said armature, each or" said coil sorings having a substantially full number of turns and the free ends of said turns are substantially arranged along a line substantially parallel to the spring axis so that by turning said springs about their axes lateral bending thereof during compression may be changed; and means cooperating with one end of one of said springs for changing the spring pressure of said one spring and thereby the lateral displacement of said armature from said electromagnetic means in said rest position of said lever.

2. An oscillating armature drive for a dry shaving apparatus comprising, in combination, support means; an elongated oscillating lever mounted intermediate the ends thereof on said support means tiltable about an axis extending transverse to the elongation of said lever; an armature fixed to one end of said lever, extending transverse thereto and having a pair of free ends having respectively end faces located substantially in a cylindrical surface having an axis coinciding with the tilting axis of said lever; electromagnetic means mounted on said support means and having a pair of poles respectively cooperating with said free ends of said armature for oscillating said lever between a rest position in which said free ends of said armature are laterally displaced with respect to said pair of poles and an attracted position in which said free ends are attracted by said poles; a pair of coil springs operatively connected at opposite ends thereof to said lever and to said support means and respectively extending to opposite sides of said lever obliquely inclined thereto so as to provide on said lever 21 force component directed toward said armature; and means cooperating with one end of one of said springs for changing the spring pressures of said one spring to change thereby the lateral displacement of said free ends of said armature from said poles in said rest position of said lever.

3. An oscillating armature drive for a dry shaving apparatus comprising, in combination, support means; and elongated oscillating lever mounted intermediate the ends thereof on said support means tiltable about an axis extendin transverse to the elongation of said lever; and armature fixed to one end of said lever, extending transverse thereto and having a pair of free ends having respectively end faces located substantially in a cylindrical surface having an axis coinciding with the tilting axis of said lever; electromagnetic means mounted on said support means and having a pair of poles respectively cooperating with said free ends of said armature for oscillating said lever between a rest position in which said free ends of said armature are laterally displaced with respect to said pair of poles and an attracted position in which said free ends are attracted by said poles; a pair of helical comression springs operatively connected to said lever and extending respectively to opposite sides thereof and being arranged obliquely inclined thereto so that the inner ends of said springs are in axial direction of said lever closer to said one end thereof than the outer ends, whereby said springs will provide a force component directed towards said armature; a pair of abutment means for each spring one fixed to said lever and one on said support means and having each an abutment face, the abutment faces in each pair of abutment means extending, when said lever is in said rest position, substantially parallel to each other and substantially normal to the axis of the spring correlated therewith and opposite ends of each spring respectively abutting against the abutment faces of said pair of abutment means correlated with said spring, whereby during oscillation of said lever said springs will not only be alternatively compressed and expanded but also be bent in direction transverse to their elongation so that by turning the springs about their axes such lateral bending may be slightly changed; and means cooperating with one abutment means of one spring for changing the position of the abutment face of said one abutment means in di rection of the axis of said one spring so as to change the compression of said one spring in the rest position of said lever relative to the compression of the other spring to change thereby the lateral displacement of said free ends of said armature from said poles in said rest position of said lever.

4. An oscillating armature drive for a dry shaving apparatus comprising, in combination, support means; an elongated oscillating lever mounted intermediate the ends thereof on said support means tiltable about an axis extending transverse to the elongation of said lever; an armature fixed to one end of said lever, extending transverse thereto and having a pair of free ends having res ectively end faces located substantially in a cylindrical surface having an axis coinciding with the tilting axis of said lever; electromagnetic means mounted on said support means and having a pair of poles respectively cooperating with said free ends of said armature for oscillating said lever between a rest position in which said free ends of said armature are laterally displaced with respect to said pair of poles and an attracted position in which said free ends are attracted by said poles; a pair of helical compression springs operatively connected to said lever and extending respectively to opposite sides thereof and being arranged obliquely inclined thereto so that the inner ends of said springs are in axial direction of said lever closer to said one end thereof than the outer ends, Whereby said springs will provide a force component directed towards said armature, each of said helical compression springs having a substantially full number of turns so that the free ends of said turns are substantially arranged along a line substantially parallel to the spring axis; a pair of abutment means for each spring one fixed to said lever and one on said support means and having each an abutment face, at least the abutment faces on said support means extending, when said lever is in said rest position, substantially normal to the axis of the spring correlated therewith and opposite ends of each spring respectively abutting against the abutment faces of said pair of abutment means correlated with said spring, whereby during oscillation of said lever said springs will not only be alternatively compressed and expanded but also be bent in direction transverse to their elongation so that by turning the springs about their axes such lateral bending may be slightly changed; and means cooperating with one abutment means of one spring for changing the position of the abutment face of said one abutment means in directicn of the axis of said one spring so as to change the compression of said one spring in the rest position of said lever relative to the compression of the other spring to change thereby the lateral displacement of said free ends of said armature from said poles in said rest position of said lever.

References Cited in the file of this patent UNITED STATES PATENTS 496,648 Gregory May 2, 1893 2,238,390 Knopp April 15, 1941 2,351,623 Martin June 20, 1944 FOREIGN PATENTS 1,200,819 France July 6, 1959 1,212,332 France Oct. 19, 1959 1,223,157 France Jan. 25, 1960 

1. AN OSCILLATING ARMATURE DRIVE FOR A DRY SHAVING APPARATUS COMPRISING, IN COMBINATION, SUPPORT MEANS; AN ELONGATED OSCILLATING LEVER MOUNTED INTERMEDIATE THE ENDS THEREOF ON SAID SUPPORT MEANS TILTABLE ABOUT AN AXIS EXTENDING TRANSVERSE TO THE ELONGATION OF SAID LEVER; AND ARMATURE FIXED TO ONE END OF SAID LEVER; ELECTROMAGNETIC MEANS MOUNTED ON SAID SUPPORT MEANS AND COOPERATING WITH SAID ARMATURE FOR OSCILLATING SAID LEVER BETWEEN A REST POSITION IN WHICH SAID ARMATURE IS LATERALLY DISPLACED WITH RESPECT TO SAID ELECTROMAGNETIC MEANS AND AN ATTRACTED POSITION IN WHICH SAID ARMATURE IS ATTRACTED BY SAID ELECTROMAGNETIC MEANS; A PAIR OF COIL SPRINGS OPERATIVELY CONNECTED AT OPPOSITE ENDS THEREOF TO SAID LEVER AND TO SAID SUPPORT MEANS AND RESPECTIVELY EXTENDING TO OPPOSITE SIDES OF SAID LEVER OBLIQUELY INCLINED THERETO SO AS TO PROVIDE ON SAID LEVER A FORCE COMPONENT DIRECTED TOWARD SAID ARMATURE, EACH OF SAID COIL SPRINGS HAVING A SUBSTANTIALLY FULL NUMBER OF TURNS AND THE FREE ENDS OF SAID TURNS ARE SUBSTANTIALLY ARRANGED ALONG A LINE SUBSTANTIALLY PARALLEL TO THE SPRING AXIS SO THAT BY TURNING SAID SPRINGS 